In recent years, there has been a rapid spread of mobile devices such as smart phones and tablet terminals. These mobile devices incorporate therein, for data storage, a semiconductor memory such as a flash memory that stores data in a non-volatile manner and a DRAM that temporarily stores data. A semiconductor memory is coupled to a controller by way of a memory interface.
In order to improve the operability of the device, a higher speed (higher frequency) of data transfer between the semiconductor memory and the controller is continuously being achieved. Accordingly, the amount of electric power consumed by the controller and the semiconductor memory is likely to increase.
To supply power to a mobile device, a battery is adopted. In order to keep a battery-driven device operating over a long period, a reduction in the power consumption in the device has been demanded.